Refrigerating apparatus



Nov. 15, 1938.

H. F. SMITH 2,136,641

REFRIGERATING APPARATUS File Dec- 21. 1936 a Sheets-Sheet 2 [W8ATTORNEYS.

Mum.

Nov. 15, 1938. H. F. SMITH REFRIGERATING APPARATUS 3 Sheets-Sheet 3Filed Dec. 21, 1936 3 mm T N m 3 V n W A X s m w ML Patented Nov. 15,1938 u UNITED STATES REFRIGERATING APPARATUS Harry F. Smith, Dayton,Ohio, assignor to General Motors Corporation, tion of Delaware Dayton,Ohio, at corpora- Application December 21, 1936, Serial No. 116,944

2 Claims.

This invention relates to heat transfer devices and particularly tocondenser constructions for'refrigerating systems.

' An object of my invention is to provide a heat exchanger of the typehaving a closed fluid conveying passage extending therethrough and whichexchanger is of improved construction and increased eiiiciency.

Another object of my invention is to provide a heat exchanger comprisinga plurality of parts adapted to be assembled together and bonded to tureto reduce the temperature gradient between certain portions of the heatexchanger.

A still further object of my invention is to increase the heat transferefficiency of a heat exchanger to thereby obtain greater capacity froman exchanger of given size or to decrease the overall dimensions of anexchanger of a predetermined capacity.

In carrying out the foregoing objects it is a still further and morespecific object of the invention to form certain portions of the fluidconveying conduits ofmy improved heat exchanger from strips of sheetmetal that are bent or folded into the desired shape and have certainportions thereof secured together to provide parts of the fluid conduitswith a plurality of closed passages.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred form of the present'invention is clearlyshown.

In the drawings:

Fig. 1 isa front elevational view of a heat exchanger constructed inaccordance with my invention;

Fig. 2 is an enlarged fragmentary end view of the heat exchangertaken'in the direction of the arrow 2 in Fig. 1 and showing the endportion partly in elevation and partly in section;

Fig. 3 is a fragmentary view of the heat exchanger partly in elevationand partly in section and taken on the line 33 of Fig.

Fig. 4 is afragmentary horizontal view of the heat exchanger taken onthe line 44 of Fig. 2;

Fig. 5 is a fragmentary sectional view similar to Fig. 4 and taken onthe line 55 of Fig. 6 showing a modifled end construction of the heatexchanger;

Fig. 6 is a fragmentary sectional view of the modified end constructionof the heat exchanger taken on the line 6-6 of Fig. 5;

Fig. 7 is a plan view of a metal strip adapted to be stampedand formedto provide a fin element for the heat exchanger;

Fig. 8 is a sectional view taken on the line 8-8 of Fig. 7 through themetal strip after having apertures stamped therein; and

Fig. 9 is a fragmentary sectional view through a fin element formed fromthe metal strip disclosed in Fig. 8 in accordance withthe invention.

Referring to the drawings, for illustrating my invention, I have shownin Fig. 1 thereof a unitary heat exchanger generally represented by thereference character I ll, such for example as a condenser for therefrigerating system. The heat exchanger Ill comprises a plurality ofsuperimposed and horizontally extending parallelly arranged closedrefrigerant conveying conduits I l. The conduits ll extend beyond theexchanger proper and have pressed sheet metal cap members l2 secured tothe ends thereof. A plurality of pipes or conduits l3 secured to certainof the cap members I2 connect the refrigerant conveying conduits H incommunicative relation toprovide a series flow for refrigerating fluidthrough the condenser or exchanger Ill. The condenser l0 may be providedwith inlet and outlet pipe connections l4 and I5 respectively at one endthereof. The heat exchanger 10 also comprises a fin arrangement foraugmenting the transfer of heat from fiuid in conduits II to the air orother cooling medium for the fluid and this arrangement includesaplurality of fins IS. A metal plate I! is secured to the fins l6 at thetop and bottom of the exchanger l0 and these plates have flanges l8extending outwardly therefrom which serve as mounting means for theexchanger orfor connecting same in an enclosed path of air such as to ashroud or the like in which is mounted an air circulating fan or blower.

Referring now to Fig. 2 of the drawings it will be noted that the fluidconduits ll extending through the heat exchanger III are flattened as at2| to provide a relatively fiat elongated passage for the flow ofrefrigerant therein. After the tubes or conduits I l have been flatteneda strip of metal 22 corrugated as at 23 is inserted in each of theconduits. The corrugations is formed in metal strip 22 provide flatportions 23 which lie against or abut the walls of conduit ll. Metalstrip 22 thus serves to d1- vide the refrigerating fluid fiowing throughconduit ll into a plurality of paths of flow to thereby awment thetransfer of heatbetween the fluid and the conduit walls and consequentlyto the fln arrangement Ii of the heat exchanger. The cap members I: ofconduits ii have an elongated portion 25 which is flattened tocorrespond to the flattened conduits II and this portion" fits over andis secured to the ends 23 of the conduits H (see Figs. 3 and 4). Theends of the elongated portions 23 of cap memhers I! are flaredoutwardlyas at 21 adjacent the exclmnger llandtheseflangesaresecuredtothe endportions of the fin arrangement It.

The fin arrangement It of the heat exchanger dhclosed comprises aplurality of corrugated or folded metal strips generaly represented bythe reference character 3i. There is a corrugated strip 3| interpowdbetween each of the superimposed-conduits II and it will be noted thateach corrmated strip provides a plurality of relatively tall thin sthrough the exchanger Ill for the flow of air or other cooling fluidtherethrough. The blank strip of metalfrom which a corrugated finelement 3i is formed is disclosed at 32 inl"lg.7.Theblank32isflrstpunchedoutas at 33 to provide a plurality of spacedapart elongated apertures or openings.

The material adiacent the lengthwise opposed walls 34 of the openingsformed by the punched out portions 33 are then bent in oppositedirections to one anotherasshownatfl and" inFig. 7 to provide legs orflanges extending at right angles to the extension of the strip 32.Alternate apertures in the blank strip 32 have the opposed walls thereofbent in opposite directions to the walls of adjacent apertures asdisclosed in Fig. 8 of the drawings for a purpose to be presentlydescribed. The punched and preformed thin metal strip 32 shown in Fig. 8is then folded or bent on lines passing through the center of anextending parallel with the extension of each aperture formed in strip32 to produce a length of corrugated strip form 3|, a fragmentaryportion of which is shown in Fig. 9 of the drawings. By referring toFig. 9 it will be seen that the folding operation performed on thepreformed fiat strip 32 causes the strip to assume a rig-sag form withthe legs or flanges 3| and 33 thereof extending in the same directionand disposed closely adjacent one another. It will also be observed thatthe material between the ends of the apertures in blank 32 and thelengthwise edges of the blank extend beyond the end walls oftheapertures as at31 to provide the corrugated structure II with raisedportions on each side of a flat substantially continuom surface formedby the legs or flanges 35 and 33. The flat substantially continuoussurfaces formed by the legs 35 and 3t inwardly ofthe extensions 31 areadapted to be placed in abutting relation with and secured to theflattenedsurface II of conduits ll.

In assembling the parts of the exchanger described a corrugated flnstrip element 3| is placed upon a plate l1 and a conduit II is. thenplaced upon the fin element 3| with the flattened wall 3i thereof inintimate contact with the substantially continuous flat surface of thefin formed by the legs 33 and 3'. Another fin element or structure 3| isthen placed over the conduit ll and the superimposing operationsdescribed are contimied until a heat exchanger of a predetermined sizeis assembled. The cap members I2 I with the conduits l3 secured theretoare then asof this invention in order to permit the substantiallycontinuous flat portions formed by legs 35 and 36 to abut against theflattened portions 2| of the conduits. The extending portions 31 on finmembers 3i are of sufilcient length to interfere with the extendingportions 31 on other superimposed fln members 3i during the assemblyoperation. The extending portions 31 of members 3| which straddle theconduits ii are therefore telescoped together so as to be disposed incontacting relation as shown in Fig. 3. The smooth rounded end portionsof the extensions 31 permits the telescoping or interlocking thereof tobe readily carried out during the operation of assembling parts of thestructure together. This telescoping or interlocking relation of theextensions 31 with one another thus provides a continuous contacting finsurface across the plurality of spaced apart conduits ii on each side ofthe exchanger. This arrangement provides a heat exchanger or condenserstructure wherein the temperature gradient between certain portions-andrelative to other portions thereof is greatly reduced to increase theefficiency of the structure. It is obvious that the fin elements 3|afford a maximum amount of heat transfer fin surface for the exchangerl0 and provide a plurality of narrow air passages through the exchangerto thus cause substantially all air circulated through the exchanger tocontact either the fins or the closed fluid conduits there of or both.After assembling all of the parts of the exchanger structure it in themanner described these plurality of parts may be secured or bondedtogether in any conventional manner well-known to those skilled in theart and now practiced in the manufacture of such devices. For example,the various assembled parts of the structure Ill may be brazed togetherwith the aid of copper brazing material in a hydrogen furnace byinserting the structure therein or by passing same therethrough. Thisbrazing of the structure will seal the plurality of fluid conduitconnections and will provide a metal-to-m'etal contact of the finelements 3i with one another and with the conduits, II. The brazing ofthe structure will also bond the leg portions 35 and 38 of the finelements 3i to the flat lengthwise extending portion of the plate l1 tothereby provide a unitary heat exchanger of increased structuralstrength.

Referring now to Figs. 5 and 6 of the drawings it will be noted that Ihave disclosed a modified closed conduit structure for the heatexchanger iii. In this modified structure a pair of metal strips II and42 having their edges bent over to provide legs are placed together inopposed relation upon a corrugated strip 45. This strip is constructedor formed in a fashion similar to the corrugated strip 22 to provide,when brazed within strips ti and 42, a closed fluid conduit 36. Sincethe edges 43 and 44 of metal strips II and 42 are bent or disposed atright angles to the fiat longitudinally extending portions thereofa-plug or the like element 41 must be placed between the elongatedportion 25 of the cap members l2 at the point where the conduit 46 issecured to the cap members. This plug 41 closes the space between thestraight sided conduit 4B and the semi-cylindrical inner surface of theportion 25 of cap members I2.

From the foregoing it will be seen that I have provided an improved heatexchanger such as a condenser for a refrigerating system and that theimproved construction materially increases the e'tllciency of suchdevices and provides a device of increased structural strength. Byincreasing the efilciency of a heat exchanger by incorporating thereinthe maximum amount of fin surface such structures can be made small andcompact and a tinuous contacting fin surface extending entirely acrossboth sides of the exchanger and thereby decreases the temperaturegradient between portions of the exchanger. It is thus seen that theincreased eillciency of my improved heat exchanger'is due partly to theplacing of a maximum amount of fin surface extending across the sides ofthe structure. The improved heat exchanger is simple in construction andthe methods of assembling and manufacturing the same can be carried outat low cost.

While the form of embodiment ofthe invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows: 1. A unitary heat exchanger comprising incombination, a closed fluid conveying conduit having a plurality ofspaced apart portions, an element interposed between each of the spacedapart portions of said conduit, each of said elements comprising asingle strip 01 metal bent or folded in contact therewith, each of saidelements being apertured inwardly of an edge portion thereof at thepoint of said bends or folds to position an end portion of said fins instraddlingrelation to said conduit portions, and the straddling endportions of said fins of one element being telescoped a substantialdistance into the straddling end portions of another of said elements toprovide an extended contacting surface. between the fins along at leastone side of said heat exchanger.

2. A heat exchanger including a closed fluid conveying conduit having apair of elements associated therewith, each of said elements comprisinga strip of metal folded back and forth to provide a plurality of finsextending laterally from said conduit and disposed in intimate thermalcontact therewith, each of said elements being apertured inwardly of anedge portion thereof at the point of said folds to position an endportion of said fins in straddling relation to said conduit, and thestraddling end portions of said fins of one element being telescoped asubstantial distance into the straddling end portions of the other ofsaid elements to provide an extended contacting surface between the finsalong a side of said conduit.

HARRY 1". SMITH.

